One hundred sixty cubic feet of air pass through a typical clothes dryer each minute the dryer is operating. Within the dryer, this air is heated and drawn past tumbling clothes to remove moisture from the clothes. Moistened air is subsequently blown through a duct from the -dryer and the building within which the dryer sits.
Running a dryer for forty-five minutes causes 7,200 cubic feet of air to be removed from a building. Since a dryer is typically run eight times in a week, the dryer blows nearly three million cubic feet of air to the atmosphere in a year. Since much of this air is either heated or cooled by conventional HVAC systems prior to it entering the dryer, the energy waste is enormous.
The blowing of air from a building by a dryer creates a negative pressure differential that causes air to leak into a building. One common place where air can leak into a building is through vent pipes such as those associated with gas furnaces or water heaters. If one of these appliances is in use, the dryer will pull the combustion product, carbon monoxide, back into the building, perhaps with deadly consequences for the occupants of the building.